Heated well production string



Oct. 4, 1960 w. E. slEvERs HEATED WELL PRODUCTION STRING Filed Dec. 2, 1957 United States Patent O HEATED WELL PRODUCTION STRING William E. Sievers, 5140 Vista Hermosa, Long Beach 15, Calif.

Filed Dec. 2, 1957, Ser. No. 700,152

14 Claims. (Cl. 166-60) This invention relates to improved apparatus for increasing the production of an -oil well by heating the oil as it ilows upwardly through the production string.

One of the major difficulties encountered in producing wells is the problem of preventing paraffin or other waxes from solidifying in the production string and thus restricting the oil flow passage through the string. The tendency for such solidication becomes progressively greater as the oil rises within the string, because of the fact that the ambient temperature usually decreases toward the surface of the earth. Even if the temperature is high enough at the bottom of the Well to prevent wax solidication, the temperature of the oil may gradually drop as the oil iiows upwardly, and ultimately to a temperature at which solidification will occur.

The general object of the present invention is to provide means for effectively maintaining the rising oil in a production string at a sufficiently high temperature to prevent the above discussed solidiiication of waxes. For this purpose, I utilize a unique type of heater unit which is connected into the production string and contains a passage through which the oil passes and within which it is heated. Preferably, several of these heaters are connected into the production string at different vertically spaced locations, so that the oil may be warmed at each of these locations, to assure its arrival at the surface of the earth without solidication of the waxes at any point.

In order to attain a most effective heating effect, I utilize a unique type of infrared heater unit, in which high intensity infrared rays are emitted directly into the flowing oil itself, to thereby heat the oil very effectively and rapidly, and without the excessive losses that occur in many other less direct types of heaters. More speciiically, the heater includes one or more electrically energized infrared lamps, whose rays are able to pass along a specially provided light passing path extending from the lamps and into a passage in the heater through which the oil flows. The lamps may be protected against direct Contact with the oil by means of a wall which is adapted to pass infrared rays therethrough, and is usually also of a light passing material, such as quartz, high temperature resistant glass, or the like. This infrared ray passing wall may take the form of a vertically extending tube through which the oil ows upwardly, with the infrared lamps being positioned about the tube. Desirably, the oil passage through the heater is so located as to pass therethrough the sucker rods for actuating the usual production pump. Also, the pump itself may be adapted for withdrawal upwardly through the heater passage if desired.

Preferably, the lamps 4are of the recently developed quartz tube type, to thus attain the advantages flowing from the very smallsize of these lamps as compared with their capacity for emitting infrared rays in extremely high concentrations. These quartz tube lamps may be positioned at the outside of the inner oil passing tube, typically in vertically extending positions, and may be carried by a replaceable sealed lamp unit, which can be removed easily and quickly from the housing of the heater for replacement.

The above and other features of the present invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawing in which:

Fig. l shows the production string of a well, having heater units constructed in accordance with the invention;

Fig. 2 is an enlarged fragmentary view, partially broken away, showing one of the heater units of the Fig. 1 string;

Fig. 3 is a horizontal section taken on line 3 3 of Fig. 2; and

Fig. 4 is a perspective view showing the inner removable infrared lamp unit of the heater device.

Referring first to Fig. 1, I have shown at 10 a conventional oil well, having the usual tubular casing 11, which is usually connected to a conventional perforated liner 12 at the production zone (though the present heater is of course also usable in open hole wells, in which there is no liner). As will be understood, the production oil ows from the formation 13 through apertures 14 in liner 12,` and into the well, to enter the lower end of the production string 15 at 20 and flow upwardly therethrough to the surface of the earth. The production string includes a large number of tubing or pipe sections represented at 16, each of these sections having upper and lower threaded ends 17 and 18 so that successive sections may be threadedly interconnected at joints 19 to form the composite vertically extending tubular production string through which the upowing oil passes.

At its lower end, the production string carries or includes a production pump of any conventional type, and typically represented at 21 in Fig. l. This pump 21 may be of the type that is removably contained within an outer tubular housing 22, and which seats downwardly against an annular seat 23 at the lower end of housing 22. The pump 21 can then take suction through the open lower end 20 of housing 22. Pump 2l may contain the usual vertically reciprocable piston represented at 24, which piston is reciprocated vertically by the usual sucker rod represented at 25 and formed of a series of Ithreadedly interconnected sucker rod sections. The entire pump unit 21 may be of a small enough diameter to be withdrawable upwardly from housing 22 and through the vertically extending passage in the production string to the surface of the earth, so that lthe pump may be completely withdrawn from the well without removing the production string.

In the particular installation represented in Fig. l, it may be assumed that `as the production oil flows into the lower end of string 15, the oil is at a sufficiently high temperature to assure 'against the solidification or settling out of any substantial portion of the paraiiin or other waxes contained in the oil. For instance, the ambient formation temperature, therefore the oil temperature, at the production zone may typically be about 130 F. As the oil is forced upwardly through the production string 15 by means of pump 21, the ambient temperature becomes progressively lower, until ultimately the ambient temperature and the oil temperature may fall to a low enough value to cause some of the waxes and paraflin to solidify and thus tend to accumulate within the interior of the production string. For instance, when the upowing production oil reaches the level represented at 26 in Fig. 1, the oil may have fallen in temperature to a value around F., which in the case of thisy particular fluid may be low enough to cause solidication of some of the waxes. In order to prevent such l; solidification, I provide at this location 26, a heater unit 27, which acts to reheat the upflowing oil, say to the original 130 F., so that no solidification will occur for a considerable distance upwardly beyond heater 27. At another location spaced above the first mentioned heater 27, there may be connected into the'production string a second and identical heater 27a, which is positioned to receive the upflowing oil after it has again fallento a critical lower temperature (say 90 Fl), and to again heat it to a desired upper value (say 130 F.). heaters 2'?, 27a, ctc. are provided at as' many different locations along the vertical extent of thek production string as are necessary to deliver the oil to the'surface of the earth without solidification of any substantial portion of the waxes: Thus, the heaters serve to maintain the interior of the production string free ofsolidified `waxes, and thus assure a continued maximum rate of production.

Referring now to Fig. 2, each of the heater units 27, 27a, etc. includes an outer rigid metal body or' housing 28, having ya cover section 29. The main section 28 of the housing is tubular, and is of straight cyclindrical vertically extending configuration except at the lower end 30 of housing 27 where it has a frustro conical downwardly tapering portion.- The upper cover section- 29 of the housing tapers upwardly, and is threadedly connected lat 31 to housing section 23 with a fluid tight seal being provided at the threaded joint by an annular seal ring represented' at' 32. The lower housing section 2S is annularly welded at 33 to a vertically extending rigid metal pipe 34, which is concentric With housing section 23 and has a lower threaded end 3S threadedly connectable to the upper threaded 3nd 17 of one of the tubing sections 16. Similarly, the upper cover section 29 of the housing has a rigid metal tub-e or pipe section 36, which is aligned vertically with lower tube 34 in the assembled condition of the apparatus, and which has an. upper threaded end 37 connectable to the threaded end 18 of one of the sections 16 of the production string. Tube 36 is rigidly connected in some suitable manner to cover section 29 of the housing, as by an annular weld represented at 38. The lower annular end face 39 of tube 36 is spaced a substantial distance above the upper annular end face 40 of lower tube 34, to provide a space between these two tubes 36 and 34 through which infrared rays may pass radially inwardly into the oil which is flowing upwardly through the heater.

For providing the infrared rays which are utilized to heat the oil, there is removably positioned within housing 28 a preferably sealed type of infrared unit 41, which may be annular and externally and internally cylindrical, as represented in Fig. 4. About the outside of this unit 41, there may be provided a tubular cylindrical sleeve of asbestos 42, for minimizing the transmission of heat radially outwardly from unit 41. The unit 41 typically includes a tubular and preferably straight. cylindrical vertically extending inner tube 43, desirably formed of quartz or high temperature resistant glass, and whose inner diameter corresponds approximately toy the external diameter of tubes 34 and 36 to be. received thereabout. Concentric with and spaced outwardly from inner tube 43, theY unit 41 includes a tubular. and

-preferably straight cylindrical outer wall 44, typically formed of a metal such las aluminum which is highly polished on its inner surface 45 to reflect' infrared rays radially inwardly toward the interior ofV tube 43'. The asbestos sleeve 42 fits closely about outer wall 44 of unit 41, and is itself of :an external dimensiontofit closely within the straight cylindrical portion of outer housing 25.

Radially between theV inner and'outer'wallsl 43v and 44 of unit 41, this unit includes a series of evenly circularly spaced electrically energized infrared lamps 46. rIhese lamps 46 are of the quartz tube type, each including a vertically extending quartz tube 47 within' whichl a vertically extending tungsten filament 48 extends at a properly centered location. The filament 48 is maintained TheseV in its centered position by positioning discs 49 located at vertically spaced locations, with the upper and lower ends of filament 48 being connected to upper and lower metal end parts or contacts 5l). The interior of thc quartz tube 47 is of course sealed against communication with the outside of the tube, and contains a suitable inert gas. The several quartz tube. infrared lamps 46 may extend parallel to one another, and parallel to the main axis 51 of tubes 43, 44 and the various other vertically extending portions of the apparatus. The upper and lower ends Sfl'of the lamps 46 are embedded Within and retained by a pair of upper and lower essentially annular rings 52 formedzof highL temperature resistant porcelain or other ceramic, or any other suitable material, with upper and lower typically metal rings 53being provided above and beneath the two ceramic rings 52 respectively. The two rings 52 are sealed to parts 43, 44 and 53 continuously about the annular extent of rings 52, as by fuse bonding of rings 52 to the other parts, to thus form a sealed unit containing lamps 46. The materal of this unit may contain a clear light passing liquid 54, which fills the space radially between parts 43 and 44, and about the various lamps 46, to function as a cooling liquid for preventing overheating of lampsV 47. This cooling liquid may typically be glycerine. At l'he under side of the upper ring 52, and at the upper side of the lowerv ring 52, there may be provided a pair of asbestos rings 55 Within the sealed unit, for minimizing the transmission of heattoward the end terminals 50 of the lamps, which terminals can not withstand the very high temperatures developed by theV central portions of the lamps. The energizing wires 56 connected to terminals Sil may extend outwardly in scaled relation through rings 52 and 53, and then out through sealed openings 57 in housing suction 28, to extend upwardly to the surface of the earth to an electrical energizing source. Preferably, all of the lamps 46 are connected in parallel to the power source, which may be a conventional volt A.C. source. Also, there is preferably connected into this circuit, within the heater unit 27, a thermostat 58, whose temperature responsive element may be responsive to changes in the temperature of tube 36 and therefore the oil contained within that tube, and which acts to automatically energize and deenergize the lamps 46 as needed to maintain a high enough oil temperature to prevent solidification of waxes from the oil.

Each of the lamps 46 yacts to emit infrared rays at ,only its vertically intermediate portion, specifically from an upper point 60 to a lower point 61. This intermediate ray emitting portion 60 to 61 of each lamp is located directly radially or horizontally opposite, and is vertically co-extensive with, the space between tubes 34l and 36, so that the rays emitted by lamps 46 may pass directly radially inwardly into the oil which is flowing upwardly through heater 27. Tubes 43 and 47, and liquid 54, are materials which readily pass light, and especially infrared rays, inwardly to the upflowing oil. The tubes 43 and 47 may be formed of translucent or transparent quartz. As an example, the tubular quartz lamps 46 may typically be the type of lamp sold by General Electric as lamp No. 500T3, which draws 500 watts, and has a lighted length of five inches.

When the sealed unit 41 is positioned within housing 28, the unit 41 is supported by engagement of lower ring 53 with a shoulder 62 formed on tube 34. When upper cover 29 and its carried tube 36 are attached to housing 28, the unit 41 is held down by engagement of an annular shoulder 63 on tube 36 with ring 53. In this condition, fluid tight annular seals are formed between unit 41 and tubes 34 and 36 by means of annular seal rings 64, typically rubber O-rings, which prevent any of the upflowing production fiuid from leaving the inner heater passage formed by tubes 34 and 36 and quartz tube 43.

To now describe the manner of use of the illustrated apparatus, `assume that the production string 15 is assembled vas shown in Fig. 1, including pump 21, heaters Z7, 27a, etc. The sucker rod 25 is then vertically reciprocated by the usual actuating mechanism at the surface of the earth (not shown), to vertically reciprocate Ithe piston 24 of pump 21, and thus cause oil to be taken from the production zone and be pumped upwardly through string 15. When this oil reaches the lowermost heater unit 27, the oil flows upwardly through tube 34, then through tube 43,l and then through tube 36, to finally enter the next successive section 16 of the string for further upward movement. As the oil passes through the exposed portion of quartz tube 43 within heater device 27, the infrared rays from lamps 46 pass radially in- Wardly into the oil, and thus veryA directly and positively, and very rapidly, heat the oil to a desired increased temperature. By reason of the infrared character of the heating rays, the heat need not be transmitted by conduction through the wall 4 3, etc., but instead can pass as these infrared rays directly into the oil. Since the oil is so colored as to readily absorb the infrared rays, the heating effect is highly efficient and effective. The polished inner surface 45 of aluminum tube 44 assures against the radially outward emission of any of the infrared rays, and instead reflects those rays radially inwardly, so that very high intensity heating rays are directed against the upflowing oil. This heating effect of the infrared rays raises .the temperature of the oil to a high enough value to prevent the solidilication of any of the waxes or other materials from the oil until the next successive heater 27a is reached. In this way, the ternperature is maintained high enough, through the entire production string to prevent solidification of the waxes.

The type of infrared lamps utilized in this device have very long life, and therefore do not need to be replaced at very frequent intervals. However, when it is necessary to replace the lamps in one of the heaters 27, this may be effected very simply by merely unscrewing the upper cover section 29 from housing section Z8, so that the entire unit 41 may then be withdrawn upwardly from the housing and maybe replaced by another unit 41, following which cover 29 and its carried tube 36 may be screwed into position to ready the entire unit for reuse.

If it becomes desirable to remove pump 21 from the well, this may be done without removing any ofthe other apparatus, since the pump is small enough in horizontal section to be withdrawable upwardly through the entire string, and through tubes 34, 36 and 43 of the heaters, to the surface of the earth. Also, if it becomes desirable to feed a solvent or well cleaning liquid into the well, this may be done by merely unseating pump 21 (by pull ing upwardly a short distance on sucker rod 25) and then passing the liquid downwardly through string 15 l and past the pump to the production zone of the well.

During such downward llow of the liquid, it may be progressively heated by heaters 27, 27a, etc., to maximize Athe cleaning effect attained by the liquid.

I claim:

l. For use with a tubular production string extending downwardly within va well and through which production oil from the well passes upwardly to the surface of the earth; apparatus comprising a heater unit, including an outer essentially tubular body, threaded connections carried by the body at its upper and lower ends for attaching said body into a tubular production string so that oil flowing upwardly through the string passes through said body, an infrared ray passing tube extending vertically within said body mounted in lluid passing relation with respect to said upper and lower connections so that said upflowing oil passes through said tube, there being a lamps, an outer tube within the body and extending about said ray passing tube and said lamps and between said tube and said body and having reflector means at its inner side reflecting the rays from said lamps inwardly toward the oil in the ray passing tube, means connecting said ray passing tube and said outer tube together at their upper and lower ends land in a relation forming with said connected tubes and said lamps a sealed unit within the interior of which the lamps are sealed, said sealed unit being removable as a unit from said body for replacement, and said body including two sections one of which is detach-able from the other section to allow removal of said sealed unit.

2. For use with a tubular production string extending downwardly within a well and through which production oil from the well passes upwardly to the surface of the earth; a heater unit including an outer essentially tubular tbody, threaded connections carried by the body at its upper and lower ends for attaching said body into a tubular production string so that oil llowing upwardly through the string passes through said body, a tube formed of a material essentially transparent to infrared rays and extending vertically within said body and mounted in fluid passing relation with respect to said upper and lower connections so that said uptlowing oil passes through said tube, there being a space between said tube and body, a plurality of circularly spaced vertically extending quartz tube infrared lamps spaced about said ray passing tube and within said space between the tube and body at a location to direct infrared rays into said ray passing tube to heat the oil therein, and means for conducting energizing current to said lamps.

3. A heater unit as recited in claim 2, including an outer tube within the body `and extending about said ray passing tube and said lamps and between said tube and said body and having reflector means at its inner side reflecting the rays from said lamps inwardly toward the oil in the ray passing tube.

4. For use with a tubular production string extending downwardly within a well and through which production oil from the well passes upwardly to the surface of the earth; a heater unit including an outer essentially tubular body, threaded connections carried by the body at its upper and lower ends for attaching said body into a tubular production string so that oil flowing upwardly through the string passes through said body, a tube formed of a material essentially transparent to infrared rays and extending vertically within said body and mounted in fluid passing relation with respect to said upper and lower connections so that said upilowing oil.

passes through said tube, there being a space between said tube and body, a plurality of circularly spaced vertically extending quartz tube infrared lamps spaced about said ray passing tube and within said space between the tube and body at a location to direct infrared rays into said ray passing tube to heat the oil therein, means for conducting energizing current to said lamps, and means forming with said tube and said lamps a generally annular sealed fluid tight unit in said body having said tube as its inner wall and having said lamps sealed within the interior of the unit, said sealed unit being removable as a unit from said body for replacement.

5. A heater unit as recited in claim 4, in which said sealed unit contains a liquid in contact with said lamps.

6. A heater unit as recited in claim 4, in which said body includes two sections which are detachable from one another to allow removal of said unit therefrom, said two sections carrying inner tubular elements projecting into the opposite ends of said generally annular sealed unit but spaced axially apart to leave a gap therebetween for passing said rays into the ol.

7,. A heater unit as recited in claim 6, including shoulders on said two sections of the body engageable with opposite ends of said sealed unit to confine it against axial movement in the body.

8. A heater unit as recited in claim 6, including shoulders on said two sections of the body engageable with opposite ends of said sealed unit to confine it against axial movement in the body, and deformable seal rings forming fluid tight seals between said shoulders and said unit.

9. A heater unit as recited in claim 4, including an asbestos sleeve disposed about said sealed unit and between said unit and the wall of said tubular body.

10. For use with a tubular production string extending downwardly within a well and through which production oil from the well passes upwardly to the surface of the earth; a heater unit having means thereon for connecting the heater unit into said production string, said unit including a vertically extending tube formed of a material which is essentially transparent to infrared rays, said tube forming and containing a passage through which said production oil flowing through the string passes when the heater unit is connected into said string, said unit including an electrically energized infrared lamp positioned at the outside of said tube at a location to emit infrared rays directly through the ray passing wall of said tube and into the oil therein to heat the latter, said connecting means comprising two upper and lower tubular threaded fittings at the upper and lo-wer ends of the heater unit and threadedly connectable to adjoining sections `of a production string into which the heater is connected.

11. A heater unit as recited in claim 10, in which said lamp is a quartz tube infrared lamp.

12. A heater unit as recited in claim 10, in which said tube of the heater unit extends vertically at a location to be in essential alignment with the oil passage through a tubular production string into which the heater is connected so that a part may be lowered downwardly through the string and `through said passage in the tube.

13. For use with a tubular production string extending downwardly within a well and through which production oil from the well passes upwardly to the surface of the earth; a heater unit to be connected into said production string, said unit having a tubular connector fitting at at least one end thereof adapted to be detachably connected to an adjacent stand of pipe in said production string and in uid communication therewith, said unit including a vertically extending tube formed of a non-metallic material which is essentially transparent to infrared rays, said tube forming and lcontaining a passage communicating with said connector fitting and through which said production oil flowing through the string passes when the heater unit is connected into said string, said unit including an electrically energized infrared lamp positioned at the outside of said non-metallic tube at `a location to emit infrared rays directly through the ray passing wall of said tube and into the oil therein to heat the latter.

14. For use with a tubular production string extending downwardly within a well and through which production cil from the well passes upwardly to the surface of the earth; a heater unit to be connected into said production string, said unit having a tubular connector iitting at at least one end thereof adapted to be detachably connected to an adjacent stand of pipe in said production string and in fluid communication therewith, said unit including a vertically extending tube formed of a non-metallic material which is essentially transparent to infrared rays, said tube forming vand containing a passage communicating with said connector fitting and through which said production oil flowing through the string passes when the heater unit is connected into said string, said unit including an electrically energized quartz tube infrared lamp positioned at the outside of said nonmetal1ic tube at a location to emit infrared rays directly through the ray passing wall of said tube and into the oil therein to heat the latter.

References Cited in the tile of this patent UNITED STATES PATENTS lune 1954, pages 583 and 584. 

